Intramedullary devices, such as nails, rods, or pins, are often used in the medical field to treat fractures of long bones, such as in the ulna and femur. These intramedullary devices also may be used to treat periarticular fractures, such as in the distal radius and proximal humerus. Such devices are typically designed to be inserted into the medullary canal of the fractured bone and generally are fastened to the bone segments on either side of the fracture to stabilize the bone and promote proper healing.
In some cases, the bone segments on either side of a fracture are spaced apart and must be brought closer together at the fracture to promote healing. Devices have been proposed that provide compression to such bone fractures by fixing the intramedullary device to one bone segment and then moving the free bone segment towards the fixed bone segment by way of compression applied to the end of the free bone segment. The free bone segment is then secured to the intramedullary device and the fracture is allowed to heal. However, these devices may not engage the end of the free bone segment in a manner that takes into account the bone structure at the end of the bone segment or provide balanced compression.
The structure of some bones, such as the ulna and femur, include a relatively hard outer shell comprised of cortical bone, and a relatively softer portion within the shell comprised of cancellous bone. In certain portions of bone, such as periarticular areas, the cortical bone can become quite thin and brittle. Thus, care must be taken when applying a compressive force to the end of the bone not to fracture or damage the cortical bone. Applying the compressive force in an unbalanced fashion to the end of the bone can be damaging to the cortical bone and may not provide a balanced compressive force at the fracture site.
Thus, there remains a need for an intramedullary device assembly that is easy to install without the need for extensive surgical dissection, and provides appropriate and balanced compression of the bone to promote healing.